Wax is used to provide ability for toner to be fused without the need for silicone oil in the fusion rollers. This is called oil-less fusion. Chemical toner methods allow better control of wax incorporation than mechanical/conventional methods. However, it is still necessary to control the location of the wax within a toner particle. The currently available chemical toners, especially those made through the latex aggregation methods suffer from the problem that it is difficult to control the location of the wax sub-particles within the toner particle.
Fujifilm Imaging Colorants Ltd. (FFIC) and Xerox latex aggregation methods are similar in principle and although they mention the need for wax to be absent from at or near the surface of the toner particle, there is no indication that their process is able to control the location of the wax particle (or for that matter any other sub-component particles). Mitsubishi has overcome this problem to some extent by making the latex around wax seeds and further by forming a secondary layer of wax-less latex during the aggregation process. However, this does not eliminate the possibility of some wax containing latex at or near the surface of the toner particle. This approach can also lead to other problems e.g. suppressing the effect of any charge control agent and/or charge effects coming from the primary latex and colorant.
Even small amounts of wax at or near the surface can cause print quality issues and storage stability issues. As well as the location of the wax sub-particles, it is also desirable to control the location of the other base materials (sub-components). For example, it may be desirable for the charge control agent (CCA) to be near the surface. In some cases it may be desirable to have colorant particles near the surface or away from the surface depending on the tribo-electric behavior of the said colorant particles. There can be up to 6 different latex types in a toner composition. It may be desirable for some of them to be near the surface and some to be away from the surface.
This invention relates to improving the quality of the chemical toner by making structured particle where the component base materials are placed at location, within the toner particle, which result in achieving desirable product features that result in improved toner performance.